This is a genuine question but—what physical media? Blu-ray players are no longer being produced by name brands, and DVDs certainly aren't capable of storing the data.
A slowdown of bluray player releases does not mean that bluray is dead. It just means that the current market is saturated. Bluray will last as long as video game consoles will, at the minimum.
Oh yeah. They're still in stock, but there was an article not that long ago that said LG was the last in a line of name brands that have stopped producing them. So what stock is left is the last of it.
Nope. Think about it, a blu ray player reads digital data. So you just store that data on a plex server and can directplay it, including passthrough audio for lossless surround or atmost.
Difference is a streamer is concerned with max device support, minimizing bandwidth and supporting users with variable internet rates. Locally, you don't have those constraints.
Most common streamers have plex support for pretty much any video codec. But only the Shield Pro (and another device) supports lossless audio too.
I use a setup like that to make the most of my A95L TV and Denon AVR with 5.1 channels. Just make sure to use an Ethernet cable, cuz blu rays use a lot of data.